Safety mechanism for cranes



July 14, 1931. R. z. HOPKINS ET AL SAFETY MECHANISM FOR CRANES Filed July 12, 1928 Patented July 14, 1931 UNITED s'rArf s MICHIGAN PATENT OFFICE RALPH, Z, HOPKINS AND GEORGE T. DAVEY, OF DETROIT, MICHIGAN, ASSIGNOR-S TO HUDSON MOTOR CAR COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF SAFETY MECHANISM FOR CRANES Application filed July 12, 1928. Serial No.-292,249.

This invention relates to crane installations and more particularly to safety mechanism for stopping the cranesandpreventing QOllision. "i g V I In factories where travelling cranes are employed for conveying different objects from various points to a given point for as sembly together, collision between two cranes often occurs/ It is an object of the resent 1'0 invention to provide a safety mechanism for cranes which will disconnect their operatingmechanism and bring them to a stop when they have been moved toward one another to predetermined relative'positions and thereby prevent their collision. I i

' Before explaining in detail the present invention, it is to be understoodthat the invention is not'limited, in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practised or carried out in various ways. Also it is to be understood that the phraseology oriterininology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention beyond the terms of the several claims hereto appended as c'onsideredin view of the prior art and the requirementsthereof. I

' Asillustrate'd in the single figure of the accompanying drawing a crane installation embodying 1 the invention may comprise cranes 10 and 11 supported for movement along parallel tracks 12,by wheels 13 mounted upon axles 14 rotatably mounted in the frame of the cranes. Each of the cranes 10 and 11 isprovided with'isuitable, mechanism for moving themtowards and away from one another along the rails 12. This mechanism may comprise a motor 20 mounted upon the frame ofthe craneand having an armature shaft carrying a pinion 21 adapted to engage a ,r 1, gear 22 mounted upona shaft 23 which is re: tatably' mounted in the frame of the crane.

The shaft '23 is provided'at its ends with a pinion 24 adapted to engage .a gear 25' mount ed upon the end of one of the wheel axles14.-

: Inthe form illustrated, the mechanism for '50 driving'the cranes issupplied with electriseparate series to extend in the direction of cal power from a switch 30 which is connected with suitable feed lines 31. Leads 32 and 33 are provided for conveying the electrical energy'from the switch 30 to suitable electrical terminals 34 and 35 upon the crane 10.

Leads 36 and 37 are provided for conveying electrical energy from the switch 30 to suit able electrical terminals 38 and 39 upon" the crane 11; V

In accordance with the provisions of the present invention suitable mechanism is provided for disconnecting the driving mechanism for the cranes from the source of power when adjacent. cranes have moved towards one another to predetermined relative positions. For this purpose, in'the construction illustrated, switches 40 and 41 are provided in the leads 32 and 36 to the cranes 10 and 11 tivelyfi When the cranes are in operation at safe distances apart the switches 40 and 41 are provided in the lead 47 all'of which normally'are closed, but any one may be opened Thus, a coil is operatively associated vwith each of the to deenergize the coil 45.

switches 50 and is connected by leads 58 and respectively which are normally held open mechanically, as by springs 42 and 43 respec- 60 to separatestationary conductors 59 and 61 respectively.

The conductors 59 and 61 are arranged in travel of the cranes, the ends of the conductors in one series terminating at a point opposite an intermediate point of the conductors of the other series. In other words,the conductors 59 are positioned in overlapping relation to the conductors 61; The crane 10 is provided with a contact shoe 65 adapted for engagement with any. one of the conductors 61 and is connected with the positive terminal 34, as by lead 66. The crane 11 is provided with a contact shoe 67 adapted to engage with any one of the conductors 59 and is connected with the negative terminal 39,

as by a lead 68. 7

Power is supplied to the motor 20 of the crane operating mechanism by closing the switch 30. The cranes may then be moved toward and away from each other by suitable controls operated by an operator upon each crane in the usual manner. When the cranes are operating at safe distances apart, electrical energy is supplied through the leads l6 and 47 to the coil &5 thereby maintaining the switches 40 and 41 closed. The coils normally are de-energized and the switches 50, held closed mechanically. However, if the crane 10 or 11 moves toward the other so that the contact shoes and 67 engagecorrespondinglythe conductorse59 andfil, that is conductors 59 and 61 which are connected to the same coil 55 that coil is energiz'ed'to open one of the switches 50 and thus break the circuit through the coil 45 and permit the switches 40 and ll to be opened mechanically, thereby disconnecting the source of power from the mechanism for moving the cranesand causing the cranes to come to a stop.

The present invention is especially advantageous for use in a-uotmobile'plants where Overhead cranes travelling on the same tracks are employed forhandling automobile bodies and chassis. For instance the crane 10 may be achassis crane operating to lift and convey a chassis from one point to another along the assembly line, while the crane 11 may be a body crane for conveying bodies on the same assembly line, the paths of travel of the body and chassis cranes overlapping. Thus it frequently happens that one crane will overrun the other, resulting in collision and dangerous accidents.

The present invention provides a construction in which one crane can approach the other only a certain distance, such. as a minimum of ten feet. Each crane has a contact shoe travelling on a series of alined conductor rails, one series or set comprising insulated sections 59 and the other comprising insulated sections 61, and the alined sets being parallel. Pairs of these sections are independently connected and staggered so that when the contact shoes of the two cranes travel onto a staggered pair a circuit will be completed, resulting in disconnecting the power mechanism for the cranes. Assuming that it is desired to stop the cranes within a minimum of ten feet from each other, the

contact sections 59 and 61 may be twenty feet along. It will be understood that suitable brake mechanism for the crane wheels may be provided which will be actuated upon disconnecting the power mechanism.

Vhat we claim is:

1, In a crane installation, the combination of a plurality of cranes movable towards and away from one another, a source of power, mechanism for moving said cranes, means for connecting said mechanism and source of power, a device operable by said source of power for stopping said mechanism automatically, and means for connecting said device and source of power when adjacent cranes have moved to predetermined rela tive positions including a member movable with each of said cranes, and astationary control member adapted to cooperate with said movable members.

2. In a crane installation, the combination of a'plurality of cranes movable towards and away from one another, a source of electrical'power, means for connecting each of said cranes with said source of power to move the same, an electrically operable device for disconnecting the cranes and source of power including a plurality of electrical circuits, and means for closing any one of said circuits when adjacent .cranes'move to predetermined relative positions.

3. In a crane installation, the combination of a plurality of cranes movable towards and away from one another, a source. of electrical power, means for operating each of said cranes, an electrically operably device for disconnecting the crane operating mechcranes, means for connecting said mechanism with said source of power, an electrically operable device for disconnecting said mechanism and source of power including a plurality of circuits,' an electrical contact on ad.- jacent cranes connected with opposite terminals'of said power source, and a stationary member positioned to connect said contacts with any one of said circuits when said ad.- jacent cranes move to predetermined relative positions.

v 5. In a crane installation, the combination of a plurality of cranes movable towards and away from one another, a source of electrical power, mechanism for moving each of said cranes, means for connecting said mech. anism and said source of power including a switch normally open, an electrical device connected with said source of power for closing said switch, and means on adjacent cranes adapted to cooperate to disconnect said device and source of power when said cranes move topredetermined relative positions.

In a an n al t n, the mbin t on of a plurality of cranes movable towards and away from one another, a source of electrical ing in the direction of travel of said cranes,

power, mechanism for moving each of said cranes, means for connecting said mechanism and said source of power including a switch normally open, an velectrical device connected with said source of power for closing said switch, and means for deenergizing said electrical device to permit said switch to open including an electrical circuit, a separate stationary conductor connected at each end of said circuit and extendand positioned in overlapping relation,'and a separate contact on adjacent cranes adapted to engage different conductors to close said circuit when adjacent cranes are moved to predetermined relative positions.

7. In a safety mechanism for a pair of cranes travelling on the same track, the combination of electrical power mechanism for moving the. cranes, a contact shoe for each crane, a separate series of alined insulated conductors contacting with each shoe, each conductor of each series being staggered with respect to a conductor of the other series,

and independently connected thereto in cirv cuit, and means for disconnecting the power mechanism upon simultaneous contact of said shoes with any of said staggered pairs of conductors.

8. In a crane installation, the combination of a track adapted to movably support a plurality of cranes, electrically actuated means for moving said cranes towards and away from one another, an electrical supply source for supplying power to said means, an electrical circuit including mechanism for cutting off power to both of said crane actuating means simultaneously, and means adapted to form part of said circuit to control the energy supplied to said mechanism and to cause said power to be cut ofi from said crane actuating means when said cranes move to predetermined relative positions.

In testimony whereof we affix our signatures.

RALPH Z. HOPKINS. GEORGE T. DAVEY. 

